the fallout from the surprise resignation of cia director david petraeus after admitting to an extramarital affair has taken two tracks tonight. first with the bombshell landing just days after the presidential election, there is a growing course of questions from lawmakers about exactly when petraeus's affair was discovered and who in washington was told about it. then there's the fbi investigation that inadvertently exposed the whole thing. a probe into some harassing e-mails allegedly sent by petraeus's biography, paula broadwell. tonight nbc has learned who the fbi believes was on the receiving end of those e-mails. nbc news white house correspondent kristen welker has been working the story. she joins us now with the latest developments. kristen? >> reporter: lester, good evening. according to multiple government officials, the woman who made the initial complaint to the fbi is a close family friend of general petraeus, and there is no indication of anything more. now, the details are still murky, and lawmakers are demanding more answers. ♪ >> reporter: according to a senior federal